Temporomandibular disorders-Oral Medicine Lecture note

Definition of Temporomandibular disorders:
"Wide spectrum of specific and non specific disorders that produce symptoms of pain and dysfunction in muscles of mastication, temporomandibular joint and other associated structures."

Temporomandibular joint
TMJ is a true synovial joint with articular surfaces covered with fibrocartilage compared to other synovial joints which are covered by a hyaline cartilage. TMJ has bilateral articulation with a rigid end point of closure.
                Articular disc
Articular disc is composed of fibrous connective tissue and which are lack of vessels and nerves (therefore no inlflammation). Articular disc separates the joint in to two compartments. Disc can be divided in to four distinct regions. They are: anterior band, intermediate zone, posterior band and bilaminar region.
                Attachments of the disc
Medially and laterally: Poles of the condyle
Anteriorly: capsular ligament and Lateral pterygoid
Posteriorly: wall of the glenoid fossa, squamotympanic fissure, posterior surface of the condyle
                Capsule of TMJ
Composed of thin fibrous connective tissue and strongly reinforced by lateral ligaments
    Synovial membrane
Synovial membranes lines the peripheries of upper and lower joint compartments.
    Synovial fluid
Synovial fluid composed of mucopolysaccharides (hyaluronic acid).Function of Synovial fluid is Nutrition, Lubrication and Clearance.



                
             Muscles of mastication
  • Temporalis
  • Masseter
  • Medial pterygoid
  • Lateral pterigoid
Accessory muscles
  • Digastric
  • Mylohyoid
  • Geniohyoid
Blood supply to TMJ
Superficial temporal and deep auricular arteries
Innervation to TMJ
Auriculotemporal nerve.

Epidemiology of temporomandibular disorders
40-75% population has at least one sign of TMD and at least 33% has one symptom of the TMD’s. However overall prevalence of TMD complains in general population is very small and actually only 3.6%-7%.

Etiology of functional disturbances of TMJ
No single factor is responsible for the TMD’s because of its tolerance and adaptive capacity. However the insult is much more than the tolerance symptoms will appear.
Insults can be local or systemic. Generally local events can be trauma and trauma could be either microtrauma or macrotrauma. Sudden force which results in structural alteration in the joint are macrotrauma. Any small forces which act on the joint repeatedly for long time and cause TMD are micro trauma. Fon example: Bruxism, clenching.
Systemic factors also contribute to TMD’s in a significant proportion, mainly psychological factors such as anxiety and depression. However non psychological disorders also can lead to TMD’s. Eg: degenerative, endocrine, metabolic and neoplastic.

Etiologic theories of Temporomandibular disorders
Mechanical displacement theory
Neuromuscular theory
Muscular theory
Pshycological theory
Phyco-sociological theory

Current understanding about TMD etiology
It is multifactorial which interplay of anatomical, neuromuscular and psychological result in TMD. TMD passes three major stages in its disease process. They are predisposition, initiation and perpetuation.

History and Examination of TMD’s
History plays a major role in diagnosis and management of temporomandibular disorders. It is important to concentrate on presenting complaint, history of presenting complaint, history of trauma (either micro or macro trauma) and history of pain if patient present with pain complaint. Psycological history may also contribute to the diagnosis in significant proportion.

Examination of TMD’s
Examination of the TMJ should consist of inspection, palpation and auscultation. Any color change and morphological alteration in the masticatory should be noted. Particular attention must be paid for mouth opening and both comfortable and maximum unaided mouth opening should be measured. Any deviation or deflection in the mouth opening should be noted. One should not forget to palpate muscles of mastication and neck muscles too. Both joints should be palpated for tenderness and abnormalities in path of opening. Joint should be auscultated as abnormal sound as “Click” or “Crepititions” are felt.

TMJ imaging
Radiological techniques
  • Plain radiography
                Dental panoramic tomography
                TMJ views-Transcranial view, Transpharyngeal view, Transmaxillary view
  • CT scan
  • MRI scan
  • Arthrography- contrast radiography. Good to asses details of disc position. Can be double or single contrast arthrography
  • Arthroscopy
  • Bone scan
  • Ultrasound scan
Diagnostic classification of temporomandibular disorders(TMD’s)
01.TMD’s can be broadly classify in to main catagories
02.TMD articular disorders
03.Masticatory muscle disorders

Temporomandibular disorders classification (Anatomical)-by American association of orofacial pain

Congenital or developmental disorders
Aplasia-faulty or incomplete development eg: hemifacial microsomia or first and second branchial arch syndromes
Hypoplasia-  incomplete or underdevelopment. Can be associated with certain syndromes or could be due to trauma or infection.
Hyperplasia- over development that is non neoplastic increase in number of normal cells.
Neoplasia
            
           Disc derangement disorders
Described as abrupt alteration or interference of the disc condyle structural relation during mandibular movements in opening and closing. (During translational movements)
Disc displacement with reduction
Disc displacement without reduction

         Disc displacement with reduction
Disc is displaced temporarily anterior than normal. When the mouth is opened displaced disc reduces or improves its structural relationship with the condyle.

Symptoms
Majority are symptomless. However some may develop pain.

Diagnostic criteria
Reproducible joint noise which occurs usually, at variable positions during opening and closing the mandibular movements.
Soft tissue imaging revealing anteriorly displaced disc which improves its position during mouth opening (MRI or Arthrography shows the joint space in drop shape) and hard tissue imaging without showing any degenerative changes.

Other diagnostic criteria
Pain if present precipitated by movement
Deviation of the mandible during movement coincide with click
No restriction of the mandibular movements
Episodic and momentary catching of smooth jaw movements during mouth opening that self reduces with voluntary mandibular repositioning.

Differential diagnosis
Anatomic variation
Osteoarthritis

Disc displacement without reduction
Disc displacement without reduction is an altered or misarranged disc condyle relation that is maintained mandibular translation. Disc is non reducing or permanently displaced and disc position does not improve with mandibular movement.

Sign and symptoms
No click
Mouth opening restricted.
Marked limitation of the laterotrution of the mouth (towards the opposite side)
Pain if tries to open the mouth
Jaw deflects to the affected side.
Some patient will achieve normal opening with time.

Diagnostic criteria
Persistant limited mouth opening with history of sudden onset(Less than 35mm)
Deflection towards the affected side of the mouth.
Marked limitation of the laterotrution of the mouth (towards the opposite side)
Soft tissue imaging shows the non reducing disc.

Other diagnostic criteria
Pain which increase with forceful mouth opening
History of clicking ceased with locking
Pain on palpation of on the joint
Moderate arthritic changes in hard tissue imaging

Differential diagnosis
Acute syanovitis
Myospasm

TMJ dislocation
The condition which condyle is positioned anterior to the articular eminence and is unable to return to closed position.
Dislocation manifest clinically as an inability to close the mouth and duration of dislocation may be momentary or prolonged.

Inflammatory disorders
Capsulitis/Syanovitis
Polyarthritides eg: Rheumatoid arthritis.Gout

Capsulitis and syanovitis
Capsulitis is inflammation capsular ligament
Syanovitis is inflammation of syanovial membrane.
It is impossible to differentiate these two conditions

Symptoms and Signs
Localized TMJ pain that is increased by palpation and during function
No extensive arthritic changes in hard tissue imaging
May accompany TMJ pain during rest, limited motion of joint, fluctuation swelling, pain in the ear.

Differential diagnosis
Osteoarthritis
Polyarthritis
Ear infection
Neoplasia

Polyarthritides

Joint inflammation and structural changes caused by and generalized,systemic polyarthritic condition such as
Rhematoid arthritis
Juvenile Rheumatoid arthritis ( Still’s disease)
Spondyloarthropathies (ankylosing spondylitis, psoriatic arthritis, infectious arthritis)
Crystal induced diseases(Gout and chondrocalcinosis)
Other connective tissue discorders (Scleraderma,Sjogren’s disease,SLE)

Diagnostic criteria for polyarthritides
Pain with mandinular function
Point tenderness in palpation
Limited motion
Radiological changes
Sometimes pain at rest
Other joint involvement
Positive serology
Crepetitions with mandibular function

Osteoarthritis
Osteoarthritis is non inflammatory arthritic condition. This can be primary or secondary.

Primary osteoarthritis
A degenerative condition characterized by deterioration and abrasion of articular tissue and simultaneous remodeling of the underlying subchondral bone due to overloading of the remodeling mechanism. No identifiable systemic and local cause can be found.

Diagnostic criteria
Pain with function
Tenderness over the joint
No identifiable etiology
Joint crepetition

Radiological evidence
                Subchondral sclerosis
                Osteophyte formation
                Erosion
                Joint space narrowing

Secondary osteoarthritis
An associate prior event can be identified which overload the remodeling mechanism. Such possible etiologies are trauma or infection.

Ankylosis

Fracture

Masticatory muscle disorders
Myofacial pain
Myositis
Myospasm
Myofibrotic contracture
Neoplasia

Myofacial pain or trigger point myalgia
Myofacial pain is a pain disorder involving pain referred from trigger points within myofascial structures, either local or distant from the pain. Myofacial pain syndromes are common conditions that results from small hyperplastic trigger points. this pain can be referred from irritable points or its associated fascia or other locations.

Myofacial trigger points: myofascial trigger points are local areas of firm hypersensitive bands in a muscle producing pain.

Features of a trigger point
Source of constant deep pain
Autonomic features may be present such as reddening of eyes
Presence of local twitch response
Presence of jump sign
Associated with emotional disturbances

Trigger point can be classified as “Active” or “Latent”

Active trigger points are
Responsible for spontaneous pain
Localized to 2-5mm of hypersensitive areas
Can occur in any muscle of the body but commonly seen in head, neck and shoulders

Latent trigger points are
Not a cause of clinical complaint of pain
Manual palpation demonstrates pain

Myositis: Inflammation of the muscles
Generally arises due to trauma or infection resulting limited range of jaw movements. Sometimes ossification may result due to inflammation (Myositis ossificans)

Diagnostic criteria
Pain usually continuous
Diffuse tenderness over the muscle
Increased pain with mandibular movement

Myospasm
Sudden involuntary tonic contraction of the muscle lead to shortening of the muscle and therefore limited motion.

Diagnostic criteria
Acute pain at rest with function
Markedly reduced function
Increased EMG activity

Myofibrotic contracture (Muscles undergo fibrosis)
I this condition there will be a pain less shortening of the muscle. It shows resistance to passive stretch as a result of fibrosis of tendons, ligaments and muscles. This condition usually doesn’t give pain unless stretched forcefully.

Diagnostic criteria
Limited motion
Underlying firmness on passive stretch
No pain

Management of TMD,s

Aim of management
Alleviate pain
Restore function
Resumption of normal daily activities
Management modalities vary enormously over a great modalities. Therefore selection of the most appropriate modality is very important.

Treatment modalities

Conservative
Patient education and self care
Rest and relaxation
Cognitive behavioral management
Pharmacotherapy
Occlusal therapy
Orthopedic appliances
Physiotherapy
Rehabilitation of dental deficits
Management of trigger points

Surgical
Arthrocentesis
Arthroscopy
Arthroplasty
Disectomy
Condylectomy



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